Numerous external presence detection systems in the area surrounding a vehicle are known, generally applied to observing a particular observation area external to said vehicle, which covers a blind spot that is not satisfactorily covered by the view provided by the rear-view mirrors arranged on the vehicle, in order to thus improve the conditions designed to avoid potential risks of collision with other vehicles.
In general, the solutions described in said systems do not contemplate controlling the energy power supplies associated therewith, which however is very important bearing in mind the increasing consumption demands of latest generation vehicles, owing to the large number of electrical devices incorporated therein, and the priorities assigned in case the required consumption is greater than that can be supplied, because the batteries are too run down.
One of such external presence detection devices is proposed in Patent ES-A-2158827, in the name of the current applicant, which relates to an object presence detection device, of the type mounted on an automobile, having have at least one blind spot, where the detection device is suitable for detecting an object located in said blind spot and having: a receiver suitable for detecting electromagnetic waves, with a locating device, and a photo sensor which converts said received electromagnetic waves into electrical signals, an electronic circuit which analyses said signals and emits variable output signals according to the result of said analysis. Said patent does not refer to the way in which the detection device is powered, however it does claim that the detection device is adapted to act upon the door safety locks of said automobile, to prevent a passenger from exiting the vehicle if a dangerous situation is detected.
Patent ES-A-2009417 proposes a television operated rear-view mirror apparatus for automobiles, made up of a screen arranged on the dashboard, on which the images captured by one or various cameras arranged on the rear and/or side of the vehicle can be viewed. Said cameras are powered via the screen, which in turn receives its electrical supply from the vehicle's battery, generally when the ignition key is activated, although as an alternative it is also contemplated to include an additional switch for powering the screen and, consequently, the cameras, in the event that the vehicle is stopped and the key has not been activated.
It is obvious that the power supply control system is, in this background example, very basic, since it only depends on the ignition key and said additional switch, and does not contemplate other devices or other supplementary considerations.
One of said supplementary considerations is, for example, knowing whether, apart from whether the ignition key is activated or not, a passenger, preferably the driver, is inside the vehicle.
Various proposals are known to detect the presence of said driver, one of which is included in U.S. Pat. No. 5,525,843, relating to a system and a method for detecting an occupant on a seat in the vehicle. For this purpose said seat has been provided with at least one pair of electrodes, connected to a detection circuit entrusted with detecting a change in the capacity measured between said electrodes.
A more sophisticated example of a power supply system is that proposed in Patent Application EP-A-0930200. Said document discloses a time-controlled power supply device and an operating method using such a device. The application thereof relates generally to supplying an accessory in a motorized vehicle and, although it is not specifically claimed, an external presence detector device could be understood as one of said accessories.
Said background example does not contemplate the operation of any other device that does not include a timed supply. In particular, power is supplied to an accessory for a certain time, if not too much time has elapsed, the vehicle ignition is deactivated and the vehicle is not closed. If the presence of a passenger is detected said predetermined time is restarted, and so the timer is activated again from zero. The detection of the presence of passengers is based here on the use or not of a series of devices belonging to the automobile, such as its air-conditioning.
To summarize, what said background example intends is that it is possible to use a series of electrical automobile devices when said automobile is stopped, including its ignition, thus ruling out that one of said devices is an external presence detection device designed to be used with the vehicle running.
It is interesting to provide an alternative to the prior art, which combines the advantages of the previous background examples, that is, the possibility of providing a suitable power supply to an automobile's external presence detection device, wherein the timing of said supply is only one of the possible strategies to be used, which bears in mind, in addition to other parameters, the entry and/or presence of a passenger in said automobile, and which, in short, guarantees the safety of the vehicle occupants, either when the vehicle is running or stopped, using said external presence detection device, without said device consuming an excessive amount of current.